Detection Yield and Tolerability of String Test for Diagnosis of Childhood Intrathoracic Tuberculosis

Feasibility and utility of a combined nasogastric-tube-and-string-test device for bacteriologic confirmation of pulmonary tuberculosis in young children

For microbiological confirmation of pediatric pulmonary tuberculosis (PTB), gastric aspirates (GA) are often operationally unfeasible without hospitalization, and the encapsulated orogastric string test is not easily swallowed in young children. The Combined-NasoGastric-Tube-and-String-Test (CNGTST) enables dual collection of GA and string specimens. In a prospective cohort study in Kenya, we examined its feasibility in children under five with presumptive PTB and compared the bacteriological yield of string to GA. Paired GA and string samples were successfully collected in 95.6 % (281/294) of children. Mycobacterium tuberculosis was isolated from 7.0 % (38/541) of GA and 4.3 % (23/541) of string samples, diagnosing 8.2 % (23/281) of children using GA and 5.3 % (15/281) using string. The CNGTST was feasible in nearly all children. Yield from string was two-thirds that of GA despite a half-hour median dwelling time. In settings where the feasibility of hospitalisation for GA is uncertain, the string component can be used to confirm PTB.

Machine learning to predict bacteriologic confirmation of Mycobacterium tuberculosis in infants and very young children

Diagnosis of tuberculosis (TB) among young children (<5 years) is challenging due to the paucibacillary nature of clinical disease and clinical similarities to other childhood diseases. We used machine learning to develop accurate prediction models of microbial confirmation with simply defined and easily obtainable clinical, demographic, and radiologic factors. We evaluated eleven supervised machine learning models (using stepwise regression, regularized regression, decision tree, and support vector machine approaches) to predict microbial confirmation in young children (<5 years) using samples from invasive (reference-standard) or noninvasive procedure. Models were trained and tested using data from a large prospective cohort of young children with symptoms suggestive of TB in Kenya. Model performance was evaluated using areas under the receiver operating curve (AUROC) and precision-recall curve (AUPRC), accuracy metrics. (i.e., sensitivity, specificity), F-beta scores, Cohen's Kappa, and Matthew's Correlation Coefficient. Among 262 included children, 29 (11%) were microbially confirmed using any sampling technique. Models were accurate at predicting microbial confirmation in samples obtained from invasive procedures (AUROC range: 0.84-0.90) and from noninvasive procedures (AUROC range: 0.83-0.89). History of household contact with a confirmed case of TB, immunological evidence of TB infection, and a chest x-ray consistent with TB disease were consistently influential across models. Our results suggest machine learning can accurately predict microbial confirmation of M. tuberculosis in young children using simply defined features and increase the bacteriologic yield in diagnostic cohorts. These findings may facilitate clinical decision making and guide clinical research into novel biomarkers of TB disease in young children.

Clinical and Radiologic Factors Associated With Detection of Mycobacterium tuberculosis in Children Under 5 Years old Using Invasive and Noninvasive Sample Collection Techniques-Kenya

Background

Pediatric tuberculosis (TB) remains a critical public health concern, yet bacteriologic confirmation of TB in children is challenging. Clinical, demographic, and radiological factors associated with a positive Mycobacterium tuberculosis specimen in young children (≤5 years) are poorly understood.

Methods

We conducted a prospective cohort study of young children with presumptive TB and examined clinical, demographic, and radiologic factors associated with invasive and noninvasive specimen collection techniques (gastric aspirate, induced sputum, nasopharyngeal aspirate, stool, and string test); up to 2 samples were taken per child, per technique. We estimated associations between these factors and a positive specimen for each technique using generalized estimating equations (GEEs) and logistic regression.

Results

A median (range) of 544 (507-566) samples were obtained for each specimen collection technique from 300 enrolled children; bacteriologic yield was low across all collection techniques (range, 1%-7% from Xpert MTB/RIF or culture), except for lymph node fine needle aspiration (29%) taken for children with cervical lymphadenopathy. Factors associated with positive M. tuberculosis samples across all techniques included prolonged lethargy (median [range] adjusted odds ratio [aOR], 8.1 [3.9-10.1]), history of exposure with a TB case (median [range] aOR, 6.1 [2.9-9.0]), immunologic evidence of M. tuberculosis infection (median [range] aOR, 4.6 [3.7-9.2]), large airway compression (median [range] aOR, 6.7 [4.7-9.5]), and hilar/mediastinal density (median [range] aOR, 2.9 [1.7-3.2]).

Conclusions

Identifying factors that lead to a positive M. tuberculosis specimen in very young children can inform clinical management and increase the efficiency of diagnostic testing in children being assessed for TB.

Xpert MTB/RIF Ultra assay for tuberculosis disease and rifampicin resistance in children

BACKGROUND

Every year, an estimated one million children and young adolescents become ill with tuberculosis, and around 226,000 of those children die. Xpert MTB/RIF Ultra (Xpert Ultra) is a molecular World Health Organization (WHO)-recommended rapid diagnostic test that simultaneously detects Mycobacterium tuberculosis complex and rifampicin resistance. We previously published a Cochrane Review 'Xpert MTB/RIF and Xpert MTB/RIF Ultra assays for tuberculosis disease and rifampicin resistance in children'. The current review updates evidence on the diagnostic accuracy of Xpert Ultra in children presumed to have tuberculosis disease. Parts of this review update informed the 2022 WHO updated guidance on management of tuberculosis in children and adolescents.

OBJECTIVES

To assess the diagnostic accuracy of Xpert Ultra for detecting: pulmonary tuberculosis, tuberculous meningitis, lymph node tuberculosis, and rifampicin resistance, in children with presumed tuberculosis. Secondary objectives To investigate potential sources of heterogeneity in accuracy estimates. For detection of tuberculosis, we considered age, comorbidity (HIV, severe pneumonia, and severe malnutrition), and specimen type as potential sources. To summarize the frequency of Xpert Ultra trace results.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, three other databases, and three trial registers without language restrictions to 9 March 2021.

SELECTION CRITERIA

Cross-sectional and cohort studies and randomized trials that evaluated Xpert Ultra in HIV-positive and HIV-negative children under 15 years of age. We included ongoing studies that helped us address the review objectives. We included studies evaluating sputum, gastric, stool, or nasopharyngeal specimens (pulmonary tuberculosis), cerebrospinal fluid (tuberculous meningitis), and fine needle aspirate or surgical biopsy tissue (lymph node tuberculosis). For detecting tuberculosis, reference standards were microbiological (culture) or composite reference standard; for stool, we also included Xpert Ultra performed on a routine respiratory specimen. For detecting rifampicin resistance, reference standards were drug susceptibility testing or MTBDRplus.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and, using QUADAS-2, assessed methodological quality judging risk of bias separately for each target condition and reference standard. For each target condition, we used the bivariate model to estimate summary sensitivity and specificity with 95% confidence intervals (CIs). We stratified all analyses by type of reference standard. We summarized the frequency of Xpert Ultra trace results; trace represents detection of a very low quantity of Mycobacterium tuberculosis DNA. We assessed certainty of evidence using GRADE.

MAIN RESULTS

We identified 14 studies (11 new studies since the previous review). For detection of pulmonary tuberculosis, 335 data sets (25,937 participants) were available for analysis. We did not identify any studies that evaluated Xpert Ultra accuracy for tuberculous meningitis or lymph node tuberculosis. Three studies evaluated Xpert Ultra for detection of rifampicin resistance. Ten studies (71%) took place in countries with a high tuberculosis burden based on WHO classification. Overall, risk of bias was low. Detection of pulmonary tuberculosis Sputum, 5 studies Xpert Ultra summary sensitivity verified by culture was 75.3% (95% CI 64.3 to 83.8; 127 participants; high-certainty evidence), and specificity was 97.1% (95% CI 94.7 to 98.5; 1054 participants; high-certainty evidence). Gastric aspirate, 7 studies Xpert Ultra summary sensitivity verified by culture was 70.4% (95% CI 53.9 to 82.9; 120 participants; moderate-certainty evidence), and specificity was 94.1% (95% CI 84.8 to 97.8; 870 participants; moderate-certainty evidence). Stool, 6 studies Xpert Ultra summary sensitivity verified by culture was 56.1% (95% CI 39.1 to 71.7; 200 participants; moderate-certainty evidence), and specificity was 98.0% (95% CI 93.3 to 99.4; 1232 participants; high certainty-evidence). Nasopharyngeal aspirate, 4 studies Xpert Ultra summary sensitivity verified by culture was 43.7% (95% CI 26.7 to 62.2; 46 participants; very low-certainty evidence), and specificity was 97.5% (95% CI 93.6 to 99.0; 489 participants; high-certainty evidence). Xpert Ultra sensitivity was lower against a composite than a culture reference standard for all specimen types other than nasopharyngeal aspirate, while specificity was similar against both reference standards. Interpretation of results In theory, for a population of 1000 children: • where 100 have pulmonary tuberculosis in sputum (by culture): - 101 would be Xpert Ultra-positive, and of these, 26 (26%) would not have pulmonary tuberculosis (false positive); and - 899 would be Xpert Ultra-negative, and of these, 25 (3%) would have tuberculosis (false negative). • where 100 have pulmonary tuberculosis in gastric aspirate (by culture): - 123 would be Xpert Ultra-positive, and of these, 53 (43%) would not have pulmonary tuberculosis (false positive); and - 877 would be Xpert Ultra-negative, and of these, 30 (3%) would have tuberculosis (false negative). • where 100 have pulmonary tuberculosis in stool (by culture): - 74 would be Xpert Ultra-positive, and of these, 18 (24%) would not have pulmonary tuberculosis (false positive); and - 926 would be Xpert Ultra-negative, and of these, 44 (5%) would have tuberculosis (false negative). • where 100 have pulmonary tuberculosis in nasopharyngeal aspirate (by culture): - 66 would be Xpert Ultra-positive, and of these, 22 (33%) would not have pulmonary tuberculosis (false positive); and - 934 would be Xpert Ultra-negative, and of these, 56 (6%) would have tuberculosis (false negative). Detection of rifampicin resistance Xpert Ultra sensitivity was 100% (3 studies, 3 participants; very low-certainty evidence), and specificity range was 97% to 100% (3 studies, 128 participants; low-certainty evidence). Trace results Xpert Ultra trace results, regarded as positive in children by WHO standards, were common. Xpert Ultra specificity remained high in children, despite the frequency of trace results.

AUTHORS' CONCLUSIONS

We found Xpert Ultra sensitivity to vary by specimen type, with sputum having the highest sensitivity, followed by gastric aspirate and stool. Nasopharyngeal aspirate had the lowest sensitivity. Xpert Ultra specificity was high against both microbiological and composite reference standards. However, the evidence base is still limited, and findings may be imprecise and vary by study setting. Although we found Xpert Ultra accurate for detection of rifampicin resistance, results were based on a very small number of studies that included only three children with rifampicin resistance. Therefore, findings should be interpreted with caution. Our findings provide support for the use of Xpert Ultra as an initial rapid molecular diagnostic in children being evaluated for tuberculosis.

Pediatric Tuberculosis Management: A Global Challenge or Breakthrough?

Managing pediatric tuberculosis (TB) remains a public health problem requiring urgent and long-lasting solutions as TB is one of the top ten causes of ill health and death in children as well as adolescents universally. Minors are particularly susceptible to this severe illness that can be fatal post-infection or even serve as reservoirs for future disease outbreaks. However, pediatric TB is the least prioritized in most health programs and optimal infection/disease control has been quite neglected for this specialized patient category, as most scientific and clinical research efforts focus on developing novel management strategies for adults. Moreover, the ongoing coronavirus pandemic has meaningfully hindered the gains and progress achieved with TB prophylaxis, therapy, diagnosis, and global eradication goals for all affected persons of varying age bands. Thus, the opening of novel research activities and opportunities that can provide more insight and create new knowledge specifically geared towards managing TB disease in this specialized group will significantly improve their well-being and longevity.

String test: a potentially useful tool in the diagnosis of pulmonary tuberculosis in Brazilian children and adolescents

This study investigated the potential use of the String Test (ST) for the diagnosis of pulmonary tuberculosis (PTB) in children and adolescents. This is a case series of patients aged 4-15 years presenting with clinically presumed PTB and submitted to ST in three pediatric TB referral centers in Brazil, between November 2017 and July 2020. The ST was performed in the morning, after 4-12 h of fasting, followed by ingestion of the capsule by the patient, which was attached to the patient’s malar region. The material was collected for simultaneous smear microscopy (acid-fast bacilli - AFB), culture and the molecular investigation by the GeneXpert MTB/RIF^®. Thirty-three patients with presumed PTB were included and ST was performed in 26 (78.8%) of them and 7 (21.2%) patients could not swallow the cord. The diagnosis of PTB was established in 11 (42.3%) of the 26 patients who underwent the ST. The diagnosis of PTB was confirmed (by culture or GeneXpert MTB/RIF^®) in 5 patients, 4 of whom were also positive by the ST. Two of them showed positivity by the GeneXpert MTB/RIF^® only in the ST sample. Two other patients had a positive ST following the induced sputum test (AFB, GeneXpert MTB/RIF^®, and positive culture in both specimens). Thus, ST was positive in 36.4% of the patients in whom PTB was diagnosed. ST could be a useful test for diagnosing PTB in children and adolescents.

Contribution and Acceptability of Bacteriological Collection Tools in the Diagnosis of Tuberculosis in Children Infected with HIV

OBJECTIVE

The objective of this study is to evaluate the feasibility and tolerability of new bacteriological samples to diagnose tuberculosis (TB) in HIV-infected children.

METHOD AND PATIENTS

HIV1-infected children with suspicion of TB in Universitary Hospital Sourô Sanon (Burkina Faso) were included in a prospective cohort study. Children underwent three gastric aspirates (GA) if aged <4 years; two GA, one string test (ST) if aged 4-9 years and three sputum, one ST if aged 10-13 years. All children underwent one nasopharyngeal aspirate (NPA) and one stool sample. To assess feasibility and tolerability of procedures, adverse events were identified and pain was rated on different scales. Samples were tested by microscopy, culture, GeneXpert® (Xpert®).

RESULTS

Sixty-three patients were included. Mean age was 8.92 years, 52.38% were females. Ninety-five GA, 67 sputum, 62 NPA, 60 stool and 55 ST had been performed. During sampling, the main adverse events were cough at 68/95 GA and 48/62 NPA; sneeze at 50/95 GA and 38/62 NPA and vomiting at 4/55 ST. On the behavioral scale, the average pain score during collection was 6.38/10 for GA; 7.70/10 for NPA and 1.03/10 for ST. Of the 31 cases of TB, bacteriological confirmation was made in 12 patients.

CONCLUSION

ST, stool is well-tolerated alternatives specimens for diagnosing TB in children. NPA has a poor feasibility and tolerability in children.

Sensitive and Feasible Specimen Collection and Testing Strategies for Diagnosing Tuberculosis in Young Children

IMPORTANCE

Criterion-standard specimens for tuberculosis diagnosis in young children, gastric aspirate (GA) and induced sputum, are invasive and rarely collected in resource-limited settings. A far less invasive approach to tuberculosis diagnostic testing in children younger than 5 years as sensitive as current reference standards is important to identify.

OBJECTIVE

To characterize the sensitivity of preferably minimally invasive specimen and assay combinations relative to maximum observed yield from all specimens and assays combined.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective cross-sectional diagnostic study, the reference standard was a panel of up to 2 samples of each of 6 specimen types tested for Mycobacterium tuberculosis complex by Xpert MTB/RIF assay and mycobacteria growth indicator tube culture. Multiple different combinations of specimens and tests were evaluated as index tests. A consecutive series of children was recruited from inpatient and outpatient settings in Kisumu County, Kenya, between October 2013 and August 2015. Participants were children younger than 5 years who had symptoms of tuberculosis (unexplained cough, fever, malnutrition) and parenchymal abnormality on chest radiography or who had cervical lymphadenopathy. Children with 1 or more evaluable specimen for 4 or more primary study specimen types were included in the analysis. Data were analyzed from February 2015 to October 2020.

MAIN OUTCOMES AND MEASURES

Cumulative and incremental diagnostic yield of combinations of specimen types and tests relative to the maximum observed yield.

RESULTS

Of the 300 enrolled children, the median (interquartile range) age was 2.0 (1.0-3.6) years, and 151 (50.3%) were female. A total of 294 met criteria for analysis. Of 31 participants with confirmed tuberculosis (maximum observed yield), 24 (sensitivity, 77%; interdecile range, 68%-87%) had positive results on up to 2 GA samples and 20 (sensitivity, 64%; interdecile range, 53%-76%) had positive test results on up to 2 induced sputum samples. The yields of 2 nasopharyngeal aspirate (NPA) samples (23 of 31 [sensitivity, 74%; interdecile range, 64%-84%]), of 1 NPA sample and 1 stool sample (22 of 31 [sensitivity, 71%; interdecile range, 60%-81%]), or of 1 NPA sample and 1 urine sample (21.5 of 31 [sensitivity, 69%; interdecile range, 58%-80%]) were similar to reference-standard specimens. Combining up to 2 each of GA and NPA samples had an average yield of 90% (28 of 31).

CONCLUSIONS AND RELEVANCE

NPA, in duplicate or in combination with stool or urine specimens, was readily obtainable and had diagnostic yield comparable with reference-standard specimens. This combination could improve tuberculosis diagnosis among children in resource-limited settings. Combining GA and NPA had greater yield than that of the current reference standards and may be useful in certain clinical and research settings.

Xpert MTB/RIF and Xpert MTB/RIF Ultra assays for active tuberculosis and rifampicin resistance in children

BACKGROUND

Every year, at least one million children become ill with tuberculosis and around 200,000 children die. Xpert MTB/RIF and Xpert Ultra are World Health Organization (WHO)-recommended rapid molecular tests that simultaneously detect tuberculosis and rifampicin resistance in adults and children with signs and symptoms of tuberculosis, at lower health system levels. To inform updated WHO guidelines on molecular assays, we performed a systematic review on the diagnostic accuracy of these tests in children presumed to have active tuberculosis.

OBJECTIVES

Primary objectives • To determine the diagnostic accuracy of Xpert MTB/RIF and Xpert Ultra for (a) pulmonary tuberculosis in children presumed to have tuberculosis; (b) tuberculous meningitis in children presumed to have tuberculosis; (c) lymph node tuberculosis in children presumed to have tuberculosis; and (d) rifampicin resistance in children presumed to have tuberculosis - For tuberculosis detection, index tests were used as the initial test, replacing standard practice (i.e. smear microscopy or culture) - For detection of rifampicin resistance, index tests replaced culture-based drug susceptibility testing as the initial test Secondary objectives • To compare the accuracy of Xpert MTB/RIF and Xpert Ultra for each of the four target conditions • To investigate potential sources of heterogeneity in accuracy estimates - For tuberculosis detection, we considered age, disease severity, smear-test status, HIV status, clinical setting, specimen type, high tuberculosis burden, and high tuberculosis/HIV burden - For detection of rifampicin resistance, we considered multi-drug-resistant tuberculosis burden • To compare multiple Xpert MTB/RIF or Xpert Ultra results (repeated testing) with the initial Xpert MTB/RIF or Xpert Ultra result SEARCH METHODS: We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, and the International Standard Randomized Controlled Trials Number (ISRCTN) Registry up to 29 April 2019, without language restrictions.

SELECTION CRITERIA

Randomized trials, cross-sectional trials, and cohort studies evaluating Xpert MTB/RIF or Xpert Ultra in HIV-positive and HIV-negative children younger than 15 years. Reference standards comprised culture or a composite reference standard for tuberculosis and drug susceptibility testing or MTBDRplus (molecular assay for detection of Mycobacterium tuberculosis and drug resistance) for rifampicin resistance. We included studies evaluating sputum, gastric aspirate, stool, nasopharyngeal or bronchial lavage specimens (pulmonary tuberculosis), cerebrospinal fluid (tuberculous meningitis), fine needle aspirates, or surgical biopsy tissue (lymph node tuberculosis).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality using the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2). For each target condition, we used the bivariate model to estimate pooled sensitivity and specificity with 95% confidence intervals (CIs). We stratified all analyses by type of reference standard. We assessed certainty of evidence using the GRADE approach.

MAIN RESULTS

For pulmonary tuberculosis, 299 data sets (68,544 participants) were available for analysis; for tuberculous meningitis, 10 data sets (423 participants) were available; for lymph node tuberculosis, 10 data sets (318 participants) were available; and for rifampicin resistance, 14 data sets (326 participants) were available. Thirty-nine studies (80%) took place in countries with high tuberculosis burden. Risk of bias was low except for the reference standard domain, for which risk of bias was unclear because many studies collected only one specimen for culture. Detection of pulmonary tuberculosis For sputum specimens, Xpert MTB/RIF pooled sensitivity (95% CI) and specificity (95% CI) verified by culture were 64.6% (55.3% to 72.9%) (23 studies, 493 participants; moderate-certainty evidence) and 99.0% (98.1% to 99.5%) (23 studies, 6119 participants; moderate-certainty evidence). For other specimen types (nasopharyngeal aspirate, 4 studies; gastric aspirate, 14 studies; stool, 11 studies), Xpert MTB/RIF pooled sensitivity ranged between 45.7% and 73.0%, and pooled specificity ranged between 98.1% and 99.6%. For sputum specimens, Xpert Ultra pooled sensitivity (95% CI) and specificity (95% CI) verified by culture were 72.8% (64.7% to 79.6%) (3 studies, 136 participants; low-certainty evidence) and 97.5% (95.8% to 98.5%) (3 studies, 551 participants; high-certainty evidence). For nasopharyngeal specimens, Xpert Ultra sensitivity (95% CI) and specificity (95% CI) were 45.7% (28.9% to 63.3%) and 97.5% (93.7% to 99.3%) (1 study, 195 participants). For all specimen types, Xpert MTB/RIF and Xpert Ultra sensitivity were lower against a composite reference standard than against culture. Detection of tuberculous meningitis For cerebrospinal fluid, Xpert MTB/RIF pooled sensitivity and specificity, verified by culture, were 54.0% (95% CI 27.8% to 78.2%) (6 studies, 28 participants; very low-certainty evidence) and 93.8% (95% CI 84.5% to 97.6%) (6 studies, 213 participants; low-certainty evidence). Detection of lymph node tuberculosis For lymph node aspirates or biopsies, Xpert MTB/RIF pooled sensitivity and specificity, verified by culture, were 90.4% (95% CI 55.7% to 98.6%) (6 studies, 68 participants; very low-certainty evidence) and 89.8% (95% CI 71.5% to 96.8%) (6 studies, 142 participants; low-certainty evidence). Detection of rifampicin resistance Xpert MTB/RIF pooled sensitivity and specificity were 90.0% (67.6% to 97.5%) (6 studies, 20 participants; low-certainty evidence) and 98.3% (87.7% to 99.8%) (6 studies, 203 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

We found Xpert MTB/RIF sensitivity to vary by specimen type, with gastric aspirate specimens having the highest sensitivity followed by sputum and stool, and nasopharyngeal specimens the lowest; specificity in all specimens was > 98%. Compared with Xpert MTB/RIF, Xpert Ultra sensitivity in sputum was higher and specificity slightly lower. Xpert MTB/RIF was accurate for detection of rifampicin resistance. Xpert MTB/RIF was sensitive for diagnosing lymph node tuberculosis. For children with presumed tuberculous meningitis, treatment decisions should be based on the entirety of clinical information and treatment should not be withheld based solely on an Xpert MTB/RIF result. The small numbers of studies and participants, particularly for Xpert Ultra, limits our confidence in the precision of these estimates.

The yield of Auramine O staining using led microscopy with bleach treated sputum samples for detection of pulmonary tuberculosis at St. Peter tuberculosis specialized hospital, Addis Ababa, Ethiopia

Background

Smear microscopy is the mainstay for diagnosis of Tuberculosis (TB) in Ethiopia. This technique; however, is insensitive to detect Mycobacteria from most clinical specimens. Currently, light emitting diode (LED) fluorescence microscope is advocated to be used in high Tuberculosis (TB) burden settings by World Health Organization (WHO). However, the utility of this method is not evaluated for bleach treated sputum samples in Ethiopia.

Objective

The objective of the study is to evaluate the diagnostic importance of Auramine O (AO) staining in direct and concentrated sputum against conventional Zehil-Neelsen (ZN) and culture from the sputum samples of suspected pulmonary tuberculosis patients.

Methods

A cross-sectional study was conducted on 346 adult new pulmonary TB suspected patients at St. Peter's Specialized Hospital, Addis Ababa, Ethiopia. Three sputum samples (spot-morning-spot) were collected in sterile cups for direct Zehil-Neelsen and AO staining. Morning sputum samples were used for Mycobacterial culture on Mycobacterial Growth Indicator Tube (MGIT) 960. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were evaluated against the gold standard culture method. Data were analyzed using STATA version 13.0. All statistical tests were considered as statistically significant if the two sided P-value was < 0.05.

Results

Bleach treated sputum samples with AO staining yielded more cases as compared to direct ZN and direct AO by 6.3% and 11.5%, respectively. The sensitivity of concentrated AO and direct AO were remarkably high as compared to conventional ZN (71.8% vs. 44.5% and 62.7% vs. 44.5%). The concentrated sputum with staining of AO had a high rate (18.6%) of detecting scanty graded smears as compared to conventional ZN method.

Conclusions

Our findings indicated that the concentrated sputum with AO staining yielded high rate of sensitivity (71.8%) as compared to the conventional ZN method (44.5%). Moreover, the concentrated sputum with AO staining had superior ability in detecting scanty graded smears compared to the conventional ZN method. Therefore, it is recommended to utilize AO staining with LED microscopy for better diagnosis of Acid Fast Bacilli (AFB) from TB suspected cases and patients with pauci-bacillary TB in Ethiopia.

Alternative sputum collection methods for diagnosis of childhood intrathoracic tuberculosis: a systematic literature review

BACKGROUND

Diagnosis of intrathoracic tuberculosis (ITB) is limited in children partly by their difficulty to produce sputum specimen.

OBJECTIVE

To systematically review the detection yields of mycobacterial culture and Xpert MTB/RIF from induced sputum (IS), nasopharyngeal aspirate (NPA) and gastric aspirate (GA) in children with presumptive ITB.

DESIGN

Pubmed, Embase and Biosis databases and grey literature were searched. Randomised controlled trials, cohort, cross-sectional or case control studies using IS, GA and NPA for diagnosis of ITB published between January 1990 and January 2018 were included. Data were extracted on study design, case definition of presumptive ITB, sample collection methods, outcome measures and results.

RESULTS

30 studies were selected, including 11 554 children. Detection yields for culture ranged between 1% and 30% for IS, 1% and 45% for GA and 4% and 24% for NPA. For Xpert MTB/RIF, it was between 2% and 17% for IS, 5% and 51% for GA and 3% and 8% for NPA. There was a tendency of better yields with IS when the pretest probability of ITB was low to moderate and with GA when it was high. Sampling a second specimen contributed for 6%-33% of the cumulative yield and combination of different methods significantly increase the detection yields.

CONCLUSIONS

Despite the important study heterogeneity, any of the specimen collection methods offers good potential to confirm childhood ITB. However, their operational challenges were poorly evaluated. In the absence of a sensitive non-sputum based test, only a minority of children with ITB can be confirmed.

Epidemiological aspects, clinical manifestations, and prevention of pediatric tuberculosis from the perspective of the End TB Strategy

Tuberculosis continues to be a public health priority in many countries. In 2015, tuberculosis killed 1.4 million people, including 210,000 children. Despite the recent progress made in the control of tuberculosis in Brazil, it is still one of the countries with the highest tuberculosis burdens. In 2015, there were 69,000 reported cases of tuberculosis in Brazil and tuberculosis was the cause of 4,500 deaths in the country. In 2014, the World Health Organization approved the End TB Strategy, which set a target date of 2035 for meeting its goals of reducing the tuberculosis incidence by 90% and reducing the number of tuberculosis deaths by 95%. However, to achieve those goals in Brazil, there is a need for collaboration among the various sectors involved in tuberculosis control and for the prioritization of activities, including control measures targeting the most vulnerable populations. Children are highly vulnerable to tuberculosis, and there are particularities specific to pediatric patients regarding tuberculosis development (rapid progression from infection to active disease), prevention (low effectiveness of vaccination against the pulmonary forms and limited availability of preventive treatment of latent tuberculosis infection), diagnosis (a low rate of bacteriologically confirmed diagnosis), and treatment (poor availability of child-friendly anti-tuberculosis drugs). In this review, we discuss the epidemiology, clinical manifestations, and prevention of tuberculosis in childhood and adolescence, highlighting the peculiarities of active and latent tuberculosis in those age groups, in order to prompt reflection on new approaches to the management of pediatric tuberculosis within the framework of the End TB Strategy.

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.

Challenges and Progress with Diagnosing Pulmonary Tuberculosis in Low- and Middle-Income Countries

Case finding and the diagnosis of tuberculosis (TB) are key activities to reach the World Health Organization's End TB targets by 2030. This paper focuses on the diagnosis of pulmonary TB (PTB) in low- and middle-income countries. Sputum smear microscopy, despite its many limitations, remains the primary diagnostic tool in peripheral health facilities; however, this is being replaced by molecular diagnostic techniques, particularly Xpert MTB/RIF, which allows a bacteriologically confirmed diagnosis of TB along with information about whether or not the organism is resistant to rifampicin within two hours. Other useful diagnostic tools at peripheral facilities include chest radiography, urine lipoarabinomannan (TB-LAM) in HIV-infected patients with advanced immunodeficiency, and the loop-mediated isothermal amplification (TB-LAMP) test which may be superior to smear microscopy. National Reference Laboratories work at a higher level, largely performing culture and phenotypic drug susceptibility testing which is complemented by genotypic methods such as line probe assays for detecting resistance to isoniazid, rifampicin, and second-line drugs. Tuberculin skin testing, interferon gamma release assays, and commercial serological tests are not recommended for the diagnosis of active TB. Linking diagnosis to treatment and care is often poor, and this aspect of TB management needs far more attention than it currently receives.

Feasibility of the string test for tuberculosis diagnosis in children between 4 and 14 years old

BACKGROUND

The enteric string test can be used to obtain a specimen for microbiological confirmation of tuberculosis in children, but it is not widely used for this. The aim of this analysis to evaluate this approach in children with tuberculosis symptoms.

METHODS

We conducted a cross-sectional study to assess children's ability to complete the test (feasibility), and self-reported pain (tolerability). We examined caregivers' and children's willingness to repeat the procedure (acceptability) and described the diagnostic yield of cultures for diagnostic tools. We stratified estimates by age and compared metrics to those derived for gastric aspirate (GA).

RESULTS

Among 148 children who attempted the string test, 34% successfully swallowed the capsule. Feasibility was higher among children aged 11-14 than in children 4-10 years (83% vs 22% respectively, p < 0.0001). The string test was better tolerated than GA in both age groups; however, guardians and older children reported higher rates of willingness to repeat GA than the string test (86% vs. 58% in children; 100% vs. 83% in guardians). In 9 children with a positive sputum culture, 6 had a positive string culture. The one children with a positive gastric aspirate culture also had a positive string culture.

CONCLUSION

Although the string test was generally tolerable and accepted by children and caregivers; feasibility in young children was low. Reducing the capsule size may improve test success rates in younger children.

Managing latent tuberculosis infection and tuberculosis in children

Tuberculosis (TB) is a major cause of childhood morbidity and mortality worldwide. The aim of this review is to describe the management of the child with TB and latent tuberculosis infection (LTBI). To develop this article, a working group reviewed relevant epidemiological and other scientific studies and established practices in conducting LBTI and TB in children. The article describes how to manage the child with LTBI, considering transmission and infectiousness of tuberculosis, contact screening and prioritization of contacts and recommendations on treatment of children with LTBI and how to manage the child with TB considering the susceptibility of children to developing tuberculosis, epidemiology and classification of tuberculosis in children, diagnosis and treatment.

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.